The present invention relates generally to fluorescence spectroscopy and more particularly to a method and device for detecting biological molecules and/or microorganisms present within a desired area or space using fluorescence spectroscopy.
Fluorescence spectroscopy has been used for quite some time by the medical and biological community to obtain fundamental information about conformal changes in muscles and nerves, the polarity of the surrounding environment, and the dynamic conformations of molecules in membranes. In addition, fluorescence spectroscopy has been used to characterize the physiological states of tissues using intrinsic fluorescing chomophores such as proteins, nucleic acids, coenzymes and lipid molecules.
In U.S. Pat. No. 5,131,398 to Alfano et al., which issued Jul. 21, 1992 and which is incorporated herein by reference, there is disclosed a method and apparatus for distinguishing cancerous tumors and tissue from benign tumors and tissue or normal tissue using native fluorescence. The tissue to be examined is excited with a beam of monochromatic light at 300 nanometers (nm). The intensity of the native fluorescence emitted from tissue is measured at 340 and 440 nm. The ratio of the two intensities is then calculated and used as a basis for determining if the tissue is cancerous as opposed to benign or normal. The invention is based on the discovery that when tissue is excited with monochromatic light at 300 nm, the native fluorescence spectrum over the region from about 320 nm to 600 nm for cancerous tissue is substantially different from that for tissue that is either benign or normal. The technique is useful in both in vivo and in vitro testing of human as well as animal tissue.
In presently pending U.S. patent application Ser. No. 08/102,094, which was filed Aug. 6, 1993 on behalf of inventors Robert R. Alfano et al., there is disclosed a method and system for monitoring the effects of a chemotherapeutic agent on a neoplastic medium. The method and system are premised on the discovery that chemotherapeutic agents affect the fluorescence spectroscopy of neoplastic medium and that such differences can be monitored, for example, by comparing the spectral profiles, spectral peaks, and spectral bandwidths of fluorescence at various wavelengths of the medium before and after administration of the chemotherapeutic agent.
As can readily be appreciated, it would be very useful to be able to determine whether biological molecules and/or microorganisms are present, for example, on a battlefield, in a hospital, in an operating room, in a home, in a slaughter house or in a medical office. Biological (organisms) particles can be carried in droplets of a solvent spray on a microscale such as water, organic materials (glycerol mixtures) etc. For instance, such information would be very helpful to a soldier on a battlefield who would want to know when biological weapons are being used against his positions, to a butcher or cook who would want to know if a countertop is contaminated by bacteria from raw meats or chickens or to medical personnel who would want to ensure that the levels of bacteria or toxins in an operating room are low after it has been cleaned.
Bacteria produce porphyrins in biological media (e.g., tissue, teeth). Ghadially et al., in Mechanisms involved in the production of red fluorescence of human and experimental tumors, J. Path. Bactiol., Vol. 85, pp. 77-92 (1963), indicated that this fluorescence was produced by porphyrins produced by bacteria that were present in the necrotic areas of tumors. Various regions contain large amounts of various aerobic and anaerobic bacteria. (See E. Sauerwein (ed.), "Kariologie," Thieme Verlag, Stuttgart, 1974.) Different microorganisms are able to synthesize fluorescent porphyrins, like copro- and protoporphyrins, which emit in the red spectral region. See Kjeldstad et al., Influence of pH on porphyrin production in Propionibacterium acnes, Arch. Dermatol. Res., Vol. 276, pp. 396-400 (1984); Konig et al., Fluorescence detection and photodynamic activity of endogenous protoporphyrin in human skin, Opt. Eng., Vol. 31, pp. 1470-1474 (July 1992). These porphyrins absorb mainly in the violet around 400 nm (Sorer band). See Konig et al., Fluorescence detection and photodynamic activity of endogenous protoporphyrin in human skin, Opt. Eng., Vol. 31, pp. 1470-1474 (July 1992).